Spacial and Temporal Distribution of Zooplankton Communities of Coastal Marine Waters Receiving Different Human Activities(Fish and Pearl Oyster Farmings)

摘要

Seasonal changes of zooplankton communities wens monitored at two different coastal marine areas,Uchiumi and Fukuura Bays located at the Uwa Sea,east side of Bungo Channel.They have similar habitat environments,but receive different environmental stresses from human activities since Uchiumi Bay is used as pearl oyster farming,while Fukuura Bay used as fish farming area.To analyze how different aquaculture activities affect zooplankton community,mesozooplankton was collected at the two bays by vertical net sampling(mesh size,200 urn)from May 2005 to May 2006.Microzooplankton was also sampled using Van-Dorn sampler and 40 urn-mesh net filtering.The species compositions of mesozooplankton were similar at the two sampling sites with dominance of coastal calanoid copepod,Paracalanus spp.But their population densities were markedly higher at Uchiumi Bay,and seasonal succession patterns also differed from each other.Small cyclopoid copepods,Oithona spp.were abundant at both sites,but the densities varied seasonally.On the other hand,the densities of microzooplankton including rotifers,bivalve larvae,and appendicularians were higher at Fukuura Bay.Results suggest that fish farms accompanying discharge of nutrients from additional food supply may seriously modify zooplankton community structure through accelerating the eutrophication of coastal water environment.